Electricity storage modules installed in hybrid electric automobiles and purely electric automobiles include a large number of electricity storage elements such as lithium-ion batteries and nickel-hydrogen batteries. The electricity storage elements generate heat due to internal resistance at the time of charging and discharging, and suffer more likely lifetime-related performance degradation such as a capacity reduction.
The electricity storage elements desirably have as smaller temperature rises as possible from the viewpoint of lifetime. To cool down the electricity elements, there is a method by which the electricity storage elements are thermally connected to a heat transfer plate via an elastic thermally-conductive sheet (refer to PTL 1). In the case of using such a thermally-conductive sheet, the electricity storage elements are pressed against the thermally-conductive sheet on the heat transfer plate to attach the electricity storage elements closely to the thermally-conductive sheet.